compiler/passes: clearPasses, registerPass does not attach to ModuleGraph

[alaviss]

Currently they operates on global vars:

Nim/compiler/passes.nim

Lines 60 to 69 in 1074cc1

	var
	gPasses: array[0..maxPasses - 1, TPass]
	gPassesLen*: int
	proc clearPasses*(g: ModuleGraph) =
	gPassesLen = 0
	proc registerPass*(g: ModuleGraph; p: TPass) =
	gPasses[gPassesLen] = p
	inc(gPassesLen)

Despite taking a ModuleGraph as argument.

See #8590 (comment)

[alaviss]

Looks like nimble might be bitten by this issue nim-lang/nimble#456

[timotheecour]

indeed!

[dom96]

Marking as high priority because it affects Nimble in a pretty bad way.

[LemonBoy]

The problem here is that we get a circular dependency we have to break somehow:
moduleGraphs cannot include passes because it includes reorder that in turn includes moduleGraphs.
We may:

• Move the "base" types and routines into another module
• Move processModule somewhere else
• Move the type definitions to moduleGraphs
• Make reorder a proper pass that runs before everything else (this means you lose the per-module granularity unless you add a filtering system an so on)

CC @Araq, choose your favourite option

[Araq]

I pick "Move the type definitions to moduleGraphs"